...because of the need to maintain or surpass critical mass.
It's a balancing act of quality and quantity. In terms of quantity...in the case of the Android platform (and less so, in terms of a hardware company, like Samsung) that critical mass target is a moving target. There comes a point where Apple knows it must compete with almost survival-like instinct to establish enough of a customer base or risk losing market share in one or many product lines.
But in general, I agree that Apple does not NEED to increase market share at the moment, other than specific demographics/geographies, like Spain.
Good point about critical mass... although it can be argued that Apple has a knack for developing huge interest despite not being the "leader" in a certain area.
Even if the smartphone market ended up being 90% Android and 10% Apple.... there would still be a few hundred million iPhones out there at that point. And most of those users would have their credit cards in iTunes... and developers would still be selling tons of apps... etc.
My point all along was that Apple doesn't need to have a large number on the market share chart... or even a significant number... to be successful.